KR101990679B1 - The water-borne quick-drying topcoat composition for automotive leaf-spring, and its manufacturing method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a top coat paint for a leaf spring which absorbs impact while supporting the weight of an automobile and maintaining an appropriate garage for a long period of time.
Conventionally, the oil paint is applied to the top and bottom to ensure stable quality and performance. However, recently, environmental problems such as air pollution problems have arisen and the necessity of recognition as a water-soluble paint has been recognized. Therefore, the present invention relates to a water-soluble quick-drying topcoat applicable to existing oil-based paints.
The top coat paint is a quick-drying type water-based paint which is dried within 10 minutes at room temperature. The composition comprises 50 to 60 parts by weight of an acrylic resin as a binder, 5 to 10 parts by weight of an anticorrosive pigment, 5 to 10 parts by weight of an extender pigment, 1 to 10 parts by weight of black, 0.5 to 5 parts by weight of a wetting and dispersing agent, 0.5 to 1 part by weight of a defoaming agent, 1 to 5 parts by weight of a thickener, 0.1 to 1 part by weight of a surface conditioning agent, 0.1 to 1 part by weight of a temporary antirust agent, 1 to 5 parts by weight of a water-soluble PUD binder, and 15 to 25 parts by weight of water.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-borne quick-drying topcoat composition for automobile leaf springs,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a top coat paint for a leaf spring which absorbs impact while supporting the weight of an automobile and maintaining an appropriate garage for a long period of time.

Conventionally, the oil paint is applied to the top and bottom to ensure stable quality and performance. However, recently, environmental problems such as air pollution problems have arisen and the necessity of recognition as a water-soluble paint has been recognized. Therefore, the present invention relates to a water-soluble quick-drying topcoat applicable to existing oil-based paints.

In the present invention as described above, a conventional oil-based epoxy zinc-based paint excellent in adhesion and corrosion resistance is used as a primer for protecting the surface of the leaf spring steel, and the top coat is a quick-drying paint excellent in gloss, adhesion, corrosion resistance, Type water-soluble acrylic resin is used. The top coat paint is a quick-drying type water-based paint which is dried within 10 minutes at room temperature. The composition comprises 50 to 60 parts by weight of an acrylic resin as a binder, 5 to 10 parts by weight of an anticorrosive pigment, 5 to 10 parts by weight of an extender pigment, 1 to 10 parts by weight of black, 0.5 to 5 parts by weight of a wetting and dispersing agent, 0.5 to 1 part by weight of a defoaming agent, 1 to 5 parts by weight of a thickener, 0.1 to 1 part by weight of a surface conditioning agent, 0.1 to 1 part by weight of a temporary antirust agent, 1 to 5 parts by weight of a water-soluble PUD binder, and 15 to 25 parts by weight of water.

The composition according to the present invention is excellent in interlayer adhesion to an oil-based epoxy zinc-based coating material, has an excellent appearance, and is particularly characterized in that it can be dried naturally and has excellent corrosion resistance and water resistance.

The leaf spring is an important part that is indispensable for automobiles and railway vehicles as well as various industrial machines. Up to now, it has been attempting to achieve stable quality and performance of leaf spring by applying high quality oil paint with excellent long-term corrosion resistance. In recent years, however, environmental problems such as air pollution problems have been increasingly being transformed from oil-based paints to water-soluble paints, and leaf spring producers have felt the need to develop water-based paints with oil-based paints at a performance level.

The present invention provides a water-based topcoat to be applied to such an oil-based primer, based on an oil-based epoxy zinc paint as a conventional undercoat. The water-soluble topcoat which is excellent in interlayer adhesion between the undercoat and the topcoat and which is equal to the quality when the top and bottom are oil-based is developed, thereby exhibiting better appearance and physical properties than the existing ones and lowering the VOC content. Positive contributions can be made.

The object of the present invention is to provide a coating composition which is excellent in adhesion, corrosion resistance, and water resistance, is excellent in workability, has a low fire risk, can be discharged at low temperature and room temperature, The present invention provides a water-soluble coating composition which can significantly reduce the energy consumption cost as compared with the heat drying method.

The method for producing an aqueous quick-drying coating composition for automotive leaf springs according to the present invention comprises the steps of:

(1) Step 1: 15 to 25 parts by weight of ion exchanged water, 5 to 10 parts by weight of a film forming solvent, 0.5 to 5 parts by weight of a wet dispersant, and 0.5 to 1 part by weight of an antifoaming agent are mixed and stirred at 600 to 800 rpm for 5 to 15 minutes ;

(2) Step 2: 1 to 10 parts by weight of a black pigment, 5 to 10 parts by weight of an extender pigment and 5 to 10 parts by weight of a rust preventive pigment are added to the agitated material stirred in the first step at 600 to 800 rpm for 5 to 15 minutes Stirring the mixture at 1500 to 1800 rpm for 50 to 70 minutes to disperse the mixture so that the degree of softening becomes 20 microns or less;

(3) Step 3: 50 to 60 parts by weight of a water-soluble acrylic binder, 0.1 to 1 part by weight of a temporary antirust agent, 0.1 to 1 part by weight of a neutralizing agent, 0.1 to 1 part by weight of a surface conditioner, 1 to 5 parts by weight of "NMP" free aliphatic water-soluble polyurethane dispersion binder synthesized by chain extension by reaction of polyester diol and diisocyanate, and the mixture was stirred at 600 to 800 rpm for 10 to 30 minutes And aging for 50 to 70 minutes.

The water-soluble acrylic binder to be added to the third step is an acrylic-styrene copolymer resin having a pH of 8.5 to 9.5 and a minimum film-forming temperature of 45 to 50 ° C.

The rust-preventive pigment to be added in the second step is aluminum triphosphate.

In addition, the temporary antirust agent to be added in the third step is characterized in that sodium nitrite is dissolved in ion-exchanged water to form a 15% solution.

The present invention also provides an aqueous quick-drying coating composition for automobile leaf springs made by each of the above production methods.

The configuration of the present invention as described above will be further described.

The water-soluble quick-drying coating composition of the present invention contains 50 to 60 parts by weight of a water-soluble acrylic resin so as to serve as a main binder for forming a coating film so as to impart appearance, adhesion and dryness of the coating film.

The water-soluble acrylic resin is an acrylic-styrene copolymer resin, which improves adhesion, luster and dryness of the material.

The anticorrosive pigment is a non-toxic inorganic pigment which acts to passivate the metal or to suppress the corrosion of the metal by an electric action, and is suitably 5 to 10 parts by weight. The anticorrosive pigment may be selected from zinc phosphate, aluminum triphosphate and porous silica, but aluminum triphosphate is the most excellent in the test results.

The extender pigment which can be selected from talc, barium sulfate, calcium carbonate and a mixture thereof provides a durability, a hardness and a crumb resistance of the coating film and includes 5 to 10 parts by weight.

Carbon black, iron oxide and graphite may be used as black coloring pigments for imparting hue and hiding power, but carbon black having excellent tinting strength and blackness is preferable, and it has good color and hiding power even in 1 to 10 weight parts.

0.5 to 5 parts by weight of a wetting and dispersing agent composed of a copolymer aqueous solution having a pigment-affinity group surrounds the pigment particles to chemically stabilize it to increase compatibility with the resin, wet it in water and increase the dispersing effect. Also, the wetting and dispersing agent repels each of the particles stericly and electrically, thereby inhibiting agglomeration among the particles during storage, thereby enhancing storage stability.

The thickening agent composed of associative urethane or associative acrylic or the like is 1 to 5 parts by weight, and it is possible to suppress the sedimentation of the pigment particles by imparting rigidity to the paint itself and to improve the storage property and prevent the paint from flowing vertically have.

The surface modifier which can be selected from polydimethylsiloxane solution or modified siloxane solution is 0.1 to 1 part by weight, and the surface tension is lowered so that the coating material spreads well on the material upon application.

Polyether siloxane copolymer emulsion or the like is 0.5 to 1 part by weight and removes bubbles generated during the dispersion process, storage and coating.

0.1 to 1 part by weight of a temporary antitheft agent composed of sodium nitrite inhibits corrosion of iron or metal by moisture in the paint when the water-soluble paint is dried. It is used to prevent initial bleaching and to control pH. When added in excess amount, coating stability is lowered. When added in small amount, sodium nitrite salt is dissolved in ion exchange water to make 15% solution.

5 to 10 parts by weight of one or two kinds of a film forming solvent which can be selected from texanol, ethylene glycol, propylene glycol, dipropylene glycol monoethyl ether, dipropylene glycol n-butyl ether and ethylene glycol monobutyl ether and mixtures thereof, It helps to form a homogeneous coating film by plasticizing and lowers the minimum coating film formation temperature and makes it easy to form a coating even at room temperature.

1 to 5 parts by weight of a "NMP" free aliphatic water-soluble polyurethane dispersion binder synthesized by chain elongation by reaction of a polyester diol and a diisocyanate is excellent in compatibility with a water-soluble acrylic binder and used as a modifier, Corrosion resistance and water resistance.

Water is a solvent for replacing organic solvents and plays a major role in environmentally friendly water-soluble paints and includes 15 to 25 parts by weight. In the case of general constants, it is preferable to use ion-exchanged water because it contains a job-like substance such as chlorine and may affect the corrosion resistance.

The water-soluble quick-drying top coating composition formed from the above-mentioned materials has excellent appearance, adhesion, water resistance and corrosion resistance, and can be dried at a low temperature, so that it can be used as a paint suitable for automotive metal parts such as leaf springs.

Hereinafter, the present invention will be described in detail with reference to examples.

  1) Ion-exchanged water: Water quality with a conductivity of 10 μs / cm or less

  2) Constituent solvent: propylene glycol, DOW CHEM

  3) Film forming solvent: Dipropylene Glycol n-butyl Ether, Dow CHEM

  4) Wetting and dispersing agent: aqueous solution of copolymer with pigment-affinity group, TEGO Disperse 750W, Evonic

  5) Defoamer: polyether siloxane copolymer emulsion, TEGO Foamex 805N, Evonic

  6) Black pigments: Carbon black, C / Black MA-100, Mitsubishi

  7) Anti-corrosive pigment: Zinc Phosphate, Hanchang Industrial

  8) Anti-corrosive pigment: Aluminum triphosphate, K-White 140W, TAYCA

  9) Extention Pigment: Barium sulfate, BSB-8000, Cotton

  10) Extention Pigment: Talc, Talc KCM-6300, Cotton

  11) Water-soluble acrylic binder (acrylic emulsion resin): Joncryl 8383, BASF [pH 8.0 to 8.5, solid content 40%, minimum film forming temperature 15 to 20 캜]

  12) Water-soluble acrylic binder (acrylic emulsion resin): Primal WL-100, ROHM & HAAS [pH 8.5 to 9.5, solid content 50%, minimum film forming temperature 45 to 50 캜]

  13) Water-soluble acrylic binder (acrylic emulsion resin): Joncryl 1980, BASF [pH 7.5 to 8.0, solid content 40%, minimum film forming temperature 40 to 45 캜]

  14) Sodium nitrite solution (15%), BASF

15) Neutralizing agent: ammonium hydroxide, NH ₄ OH (25%),

  16) Surface conditioner: polyether-modified polydimethylsiloxane solution, BYK-333, BYK

  17) Thickening agent: associative acrylic thickener, Acrysol RM-2020NPR, ROHM & HAAS

As shown in Table 1, the compositions 1 to 5 of the compositions 1 to 17 are added in order to the mixing container, followed by mixing and stirring at 600 to 800 rpm for 10 minutes with a dissolver. The resulting mixture is stirred at 600 to 800 rpm for 10 minutes with a dissolver and then wetted with a dissolver at 1,500 to 1,800 rpm for 1 hour to disperse the resulting mixture so that the degree of softening becomes 20 microns or less. 11 to 16 in that order, and the viscosity of the coating is adjusted to 17 while stirring at 600 to 800 rpm for 20 minutes. After the completion of the manufacturing process, test the physical properties of the designed paint and compare the standard results. The paint prepared in this manufacturing process contained a large amount of air bubbles. After aging for a certain period of time, the paint was stabilized and then a test piece was prepared to measure the physical properties.

The test specimens were prepared by degreasing the surface of the shot cold rolled steel sheet with MEK, applying a submerged epoxy zinc paint, applying a water-soluble top coat using an air spray gun to a coating thickness of 20 to 25 μm, and then drying at room temperature for 3 days Post-test.

The coating compositions obtained in Examples 1 to 4 were used to form coating films on the basic physical properties of coating materials and undercoated epoxy zinc coating films, and then the properties of the coating films were tested with these test pieces. The results of the paint and film properties test are shown in Table 2 below.

1) Adhesiveness was determined by observing the degree of detachment when it was cut off with a cellophane tape by cutting it into 100 squares in a checkerboard shape with a width of 100 mm and a length of 1 mm.

2) Impact resistance was measured by a Dupont type impact tester after one drop at 1/2 "x500 gx30 cm, and the occurrence of breakage and peeling of the coating film was examined.

3) Oil resistance was determined by immersing in crankcase oil at 65 ℃ for 1 hour.

4) The water resistance was evaluated by observing the appearance of swelling after immersing in pure water at 40 ° C for 48 hours, and after 24 hours of natural drying, cross-cut adhesion test was carried out 100/100 after cross-cut.

5) The salt-water-silence test was performed by cross-cutting the specimen with an X-ray and then observing the degree of swelling and X-ray irradiation in a saline sprayer sprayed with a 5% -sodium chloride solution at 35 ° C for 120 hours.

6) The gloss was completely dried and then measured using a polisher.

7) Storage stability was evaluated by observing the settling state of the coating composition and the degree of hardening of the sediment after placing the coating composition in a 1-liter container, sealing it and sealing it at 40 ° C for 1 month.

8) The drying property was evaluated as the fixing drying condition by applying the top coat to the submerged zinc epoxy at 25 ° C.

The results of the physical properties of the paint and the coating film prepared as described above are shown in Table 2. The nonvolatile matter had a viscosity of 70-74 KU in a Krebs-Unit viscometer with a weight ratio of 39-41%, a softness of 20 microns or less, and a specific gravity of 1.15-1.18.

As can be seen from the above results, the results of Examples 1, 2 and 3 using Joncryl 8383 and Primal WL-100 as water-soluble binders were very good, while the adhesion of Example 4 was relatively low. In the case of impact resistance, the results of Example 3 were the best, and in Example 4, the binder having a Tg (glass transition temperature) of 78 deg. C was used, and the impact resistance of the coating film was lowered. Also, the more the use of barium sulphate as an extender pigment, the lower the impact strength. In the oil resistance test, all of the examples were good, and the water resistance and the salt resistance were good in Examples 2 and 3 using the water-soluble binder Primal WL-100, and good results were obtained in all cases.

According to the above results, Examples 2 and 3 using the water-soluble acrylic binder Primal WL-100 as the water-soluble quick-drying coating composition of the present invention showed excellent adhesion, oil resistance and storage stability as shown in Table 2. Therefore, in order to complement the impact, water resistance, flame retardancy, gloss, and drying properties, the inventors used "NMP" free aliphatic water-soluble polyurethane dispersion binder synthesized by chain elongation by reaction of polyester diol with diisocyanate as follows Experiments were conducted.

1) Ion-exchanged water: Water quality with a conductivity of 10 μs / cm or less

2) Constituent solvent: Propylene Gylcol, DOW CHEM

3) Tanning solvent: Dipropylene Glycol Methyl Ether, DOW CHEM

4) Wetting and dispersing agent: aqueous solution of copolymer with pigment-affinity group, TEGO Disperse 750W, Evonic

5) Defoamer: polyether siloxane copolymer emulsion, TEGO Foamex 805N, Evonic

6) Black pigments: Carbon black, C / Black MA-100, Mitsubishi

7) Anti-corrosive pigment: Aluminum triphosphate, K-White 140W, TAYCA

8) Rustproof pigments: zinc phosphate, Zinc Phosphate, Hanchang Industrial

9) Extention Pigment: Barium sulfate, BSB-8000, Cotton

10) Extention Pigment: Talc, Talc KCM-6300, Cotton

11) Water-soluble acrylic binder: Primal WL-100, ROHM & HAAS

12) Sodium nitrite solution (15%), BASF

13) Neutralizer: Ammonium hydroxide, NH ₄ OH (25%),

14) Surface conditioner: polyether-modified polydimethylsiloxane solution, BYK-333, BYK

15) PUD binder: water soluble polyurethane dispersion, BASF [pH 8.0 ~ 9.0, solid content 35 ~ 40%, minimum film formation temperature 20 ~ 25 ℃]

16) Thickening agent: associative acrylic thickener, Acrysol RM-2020NPR, ROHM & HAAS

As shown in Table 3, 1 to 5 of the compositions 1 to 16 were added to the mixing container in order, followed by mixing and stirring at 600 to 800 rpm for 10 minutes with a dissolver. The resulting mixture is stirred at 600 to 800 rpm for 10 minutes with a dissolver and then wetted with a dissolver at 1,500 to 1,800 rpm for 1 hour to disperse the resulting mixture so that the degree of softening becomes 20 microns or less. 11 to 15 in that order, and the viscosity of the coating is adjusted to 16 while stirring at 600 to 800 rpm for 20 minutes. After the completion of the manufacturing process, test the physical properties of the designed paint and compare the standard results. The paint prepared in this manufacturing process contained a large amount of air bubbles. After aging for a certain period of time, the paint was stabilized and then a test piece was prepared to measure the physical properties.

The test specimens were prepared by degreasing the surface of the shot cold rolled steel sheet with MEK, applying a submerged epoxy zinc paint, applying a water-soluble top coat using an air spray gun to a coating thickness of 20 to 25 μm, and then drying at room temperature for 3 days Post-test.

Using the compositions of the paints obtained in Examples 5 to 7, basic physical properties and physical properties of paints were tested. The results of the paint and film properties test are shown in Table 4 below.

1) Adhesiveness was determined by observing the degree of detachment when it was cut with a cellophane tape by cutting with 100 squares in a checkerboard shape with a width of 1 mm and a length of 1 mm.

2) Impact resistance was measured by a Dupont type impact tester after one drop at 1/2 "x500 gx30 cm, and the occurrence of breakage and peeling of the coating film was examined.

3) Oil resistance was determined by immersing in crankcase oil at 65 ℃ for 1 hour.

4) The water resistance was evaluated by observing the appearance of swelling after immersing in pure water at 40 ° C for 48 hours, and after 24 hours of natural drying, cross-cut adhesion test was carried out 100/100 after cross-cut.

5) The salt-water-silence test was performed by cross-cutting the specimen with an X-ray and then observing the degree of swelling and X-ray irradiation in a saline sprayer sprayed with a 5% -sodium chloride solution at 35 ° C for 120 hours.

6) The gloss was completely dried and then measured using a polisher.

7) Storage stability was evaluated by observing the settling state of the coating composition and the degree of hardening of the sediment after placing the coating composition in a 1-liter container, sealing it and sealing it at 40 ° C for 1 month.

8) The drying property was evaluated as the fixing drying condition by applying the top coat to the submerged zinc epoxy at 25 ° C.

As shown in Table 4, 5 to 10 parts by weight of the water-soluble acrylic resin as the main binder and 50 to 60 parts by weight of the aluminum triphosphate anticorrosive pigment were used as the water-soluble quick-drying coating composition, , Adhesiveness, impact resistance, oil resistance, water resistance, salt water repellency, storage stability and drying property were also superior to those of the other examples.

The present invention can form a coating film at room temperature by lowering the minimum film forming temperature by using an optimal film forming solvent so that it can be applied to parts of automotive metal parts which are excellent in water-soluble low-temperature and normal-temperature drying conditions and excellent appearance and corrosion resistance and water resistance . In addition, "NMP" free aliphatic water-soluble polyurethane dispersion which is synthesized by chain elongation by reaction of polyester diol with diisocyanate is used as a modifier so as to have better adhesion, corrosion resistance and water resistance than water-soluble acrylic paint generally excellent in appearance So that it is excellent in physical properties and diluted with water as a water-soluble paint, so that fire hazard and VOC can be reduced and used easily.

Claims (5)

delete delete 1. A method for producing an upper coating material applied to an oil-based coating material,
(1) Step 1: 15 to 25 parts by weight of ion exchanged water, 5 to 10 parts by weight of a film forming solvent, 0.5 to 5 parts by weight of a wet dispersant, and 0.5 to 1 part by weight of an antifoaming agent are mixed and stirred at 600 to 800 rpm for 5 to 15 minutes ;
(2) Step 2: 1 to 10 parts by weight of a black pigment, 5 to 10 parts by weight of an extender pigment and 5 to 10 parts by weight of a rust preventive pigment are added to the agitated material stirred in the first step at 600 to 800 rpm for 5 to 15 minutes Stirring the mixture at 1500 to 1800 rpm for 50 to 70 minutes to disperse the mixture so that the degree of softening becomes 20 microns or less;
(3) Step 3: 50 to 60 parts by weight of a water-soluble acrylic binder, 0.1 to 1 part by weight of a temporary antirust agent, 0.1 to 1 part by weight of a neutralizing agent, 0.1 to 1 part by weight of a surface conditioner, 1 to 5 parts by weight of "NMP" free aliphatic water-soluble polyurethane dispersion binder synthesized by chain extension by reaction of polyester diol and diisocyanate, and the mixture was stirred at 600 to 800 rpm for 10 to 30 minutes Aging for 50 to 70 minutes,
The water-soluble acrylic binder to be added to the third step is an acrylic-styrene copolymer resin having a pH of 8.5 to 9.5 and a minimum film-forming temperature of 45 to 50 ° C,
The anti-corrosive pigment to be added in the second step,
Aluminum triphosphate, wherein the water-soluble quick-drying coating composition for automobile leaf spring is aluminum triphosphate. The method of claim 3,
The temporary antirust agent, which is input in the third step,
Wherein the sodium nitrite is dissolved in ion-exchange water to form a 15% solution. A water-soluble quick drying top coat composition for automobile leaf springs, which is produced by the manufacturing method according to claim 3 or 4.